Highly ordered Co nanowire arrays were grown using a direct current (DC) electrodeposition method based on an anodic aluminum oxide (AAO) template. The electrolyte consists of CoSO4 center dot 7H(2)O and H3BO3 in distilled water. Co nanowires fabricated by electrodeposition are cylindrical monocrystals with a packed surface, and behave as hcp dominant structures. The nanowires are preferentially oriented along the [1 0 0] direction. The effective demagnetizing factors parallel and perpendicular to the plane of the film are N-eff(parallel to) = 0.65 and N-eff(perpendicular to) = 0.175, respectively. The magnetic property of the Co nanowire arrays depends on the concentration of the deposition electrolyte and the deposition voltage. (C) 2011 Elsevier By. All rights reserved.